1. Field of the Invention
The present invention relates to a fuzzy control apparatus for the rotational frequency of a motor in an air jet loom, a water jet loom or the like.
2. Description of the Prior Art
In a loom or weaving machine, it is desired to set the rotational frequency of a motor as a prime mover to an optimum value. To this end, a technique has been proposed wherein the rotational frequency of a motor connected to a main shaft is varied in response to an arriving timing at which a weft yarn arrives at a predetermined position, and is disclosed, for example, in Japanese Patent Appln. Public Disclosure (KOKAI) No. 56-107046. However, determination of an optimum rotational frequency relies much upon perception and the experience of the operator. Accordingly, it is difficult to automate the control of the rotational frequency.
For example, where the arriving timing has an early average value and has a large dispersion, the rotational frequency must be raised due to the early average value while the rotational frequency must be lowered due to the large dispersion, and the two controlling directions are opposite to each other. Further, even if an identical weft yarn is used, its characteristic is different delicately whether it is inserted in a test weaving stage or it is inserted in an actual product weaving stage. Furthermore, since the productivity of a woven fabric sometimes decreases as the rotational frequency increases but increases as the rotational frequency decreases, the productivity of a woven fabric must be taken into consideration to modify the rotational frequency. From those reasons, it is very difficult to determine an appropriate rotational frequency or an appropriate modification amount to the rotational frequency of a motor.